Percussion fuze including rotary delay provisions



June 24, 1969 PERCUSSION FUZE INCLUDING ROTARY DELAY PROVISIONS Filed July 12, 19s? sheet /v /NJ/.E/V Tof? 23707726' 3Q w las. ATou g 3,451,340

June 24, 1969 e. eATeU 3,451,340

PERCUSSION FUZE INCLUDING ROTARY DELAY PROVISIONS Filed July 12, 1967 sheet ,2 of 2 /NVE/VTOI? 30711? cz Zvw ,5 Y e www, WMZ/I, SM QW Arm/wf afs 2 Claims ABSTRACT F THE DISCLOSURE A percussion fuze having a generally circular plate, an eccentric shaft extending parallel to the axis of the plate, a drum having a central aperture and rotatable about the shaft, a tiring pin, a detonator carried by the drum, a spiral spring having an end fast `with the plate and an end fast with the drum, the shaft having on its surface a sinusoidal groove the frequency axis of which extends in the direction of rotation of the drum and a lug fast with the drum and engaging in the groove, the arrangement being such that, after the spring has been wound up, a rotary movement can be imparted to the drum by the unwinding of the spring while an alternating axial movement is imparted to the drum by virtue of the engagement of said lug in the groove, thereby to bring the detonator into a position where it can engage or be engaged by the tiring pin.

This invention relates to a percussion fuze for a projectile and having a mechanism for delaying the arming of the fuze.

According to the present invention there is provided a percussion fuze comprising a generally circular plate, an eccentric shaft extending parallel to the axis of said plate and integral therewith, a drum having a central aperture and mounted for rotation about said shaft, a tiring pin, a detonator which is carried by said drum, a spiral spring of which one end is fast with the plate while the other end is fastened to the drum, said shaft being formed over at least a portion of its surface a sinusoidal groove the frequency axis of which extends in the direction of rotation of the drum and a lug fast with the drum and engaging in said groove, the arrangement being such that, after the spring has been wound up, a rotary movement can be imparted to the drum by the unwinding of the spring while an alternating axial movement is imparted to the drum by virtue of the engagement of said lug in the groove, thereby to bring the detonator into a position where it can engage or be engaged by the tiring pin.

The compound movement of the fuze drum delays the rotation of said drum by the combined effects of the sinusoidal groove on the surface, of the moment of inertia opposed to the movement by the mass of the drum and of the action of the spring, which acts both by torsion and by extension.

In order to enable the invention to be more readily understood, reference will now be made to the accompanying drawings, which illustrate diagrammatically and by way of example some embodiments thereof, and in which:

FIG. 1 is an axial section of the fuze according to the invention in a safety position;

FIG. 2 is a plan view of the fuze shown in FIG. l;

FIG. 3 is an axial section of a detail of the fuze shown in FIGS. l and 2;

FIG. 4 is another axial section of the ffuze shown in FIGS. 1 to 3, in the armed position;

3,451,340 Patented June 24, 1969 FIG. 5 is a plan view of the fuze in the position shown in FIG. 4;

FIGS. 6 and 7 show, respectively, an axial section and a plan view of another embodiment of the fuze according to the invention in its safety position;

FIGS. 8 and 9 show, respectively, an axial section and a plan view of the fuze shown in FIGS. 6 and 7 in its armed position;

FIG. 10 is a side elevation of a detail of the fuze shown in FIGS. l to 5 or 6 to 9.

Referring now to FIGS. 1 to 5, the fuze there shown comprises a plate 1 of generally circular shape which is formed with a central orice 2, and which is formed with an externally threaded collar 3, `4 for fastening the fuze to the body of a projectile (not shown). The orifice 2 is internally threaded at its lower end and the envelope 5 of an explosive relay 6 is screwed into the internally threaded lower end.

The upper face of the plate 1 is formed with an integral upstanding eccentric shaft 7 which is formed with an axial recess 8 which accommodates a spiral spring 9, the lower extremity 10 of Which passes through an aperture 11 in the plate 1, where it is held. The other extremity 12 of the spring passes through an aperture 13 arranged in the upper face of a drum 14.

The drum 14 has a central recess 15 and is mounted for rotation about the shaft 7 and caps said shaft, while a portion 16 of the drum 14 projects into the bottom of the central recess 15 and engages into the axial recess 8 of the shaft 7.

The shaft 7 is formed over at least a portion of its cylindrical surface (e.g. 7A; of its surface) with a sinusoidal groove 17 the frequency axis (x-axis) of which extends in the direction of rotation of the drum. These undulations of the groove 17 are shown in more detail in FIG. 10, which shows the plane development thereof. A lug 18 carrying a blocking head 19 is disposed n a radial aperture 21 of the drum 14 and is fast with the latter, engaging with its extremity 22 in the groove 17. The lug 18 is arranged in the drum 14 in such a manner with regard to the position and shape of the groove 17, that in the safety position (FIG. l) the drum 14 rests with its base on the upper surface of the plate 1.

The drum 14 is also formed with two eccentric orices 23 (FIGS. 1 and 2) and 24 (FIG. 4) which extend parallel to the axis of the fuze, and of which the rst (23) serves to accommodate the extremity of a plunger 25, the upper portion of which passes through an aperture in the plate 1. The lower portion of the plunger 25 is of greater diameter than the upper portion and is located below said plate 1. The aperture 24 is intended to accommodate a detonator 26 capped by a metal ring 27 (FIG. 4).

In the safety position, the detonator 26 is held in the lower portion of the orifice 24 by a ball 28 lodged partly in a transverse bore 29 of the drum 14, said bore opening into the orifice 24, the ball 28 projecting above the ring 27 and the detonator 26. The ball 28 is maintained in this position by a finger 30 extending parallel to the axis of drum `14 and fast with the plate 1. At its upper portion, the orifice 24 is closed by the base 31 of a firing pin 33 the base engaging the drum at 32. A spacing element, for example a spiral spring 34a, may be interposed between the ring 27 fast with the detonator 26 and the base 31 of the firing pin 33.

In the safety position, the plunger 25 is held in place by a shearing pin 34 extending transversely through a portion of the drum 14 and through the plunger 25. Lastly, the whole of the upper portion of the plate 1 is covered by a cap 35 held by a peripheral flange 36 of the plate 1. It will be noted that in FIGS. 2 and 5 the cap 35 is supposed to be removed, in order to render visible the other elements of the fuze located on the upper surface of plate 1.

FIGS. 6 to 9 show a modified form of embodiment of the fuze according to the invention, in which a cap 37, engaging the periphery of the plate 1 at 38, has an axial chimney 39, the base of which carries a tiring pin 40, the height of which is smaller than that of said chimney. Of the percussion elements, namely the li-ring pin and the detonator, only the latter 26 is carried by the drum 14a. In this case, the detonator 26 is fast with a metal tube 41 adapted for sliding movement in the cylindrical aperture of the drum accommodating it. It will be noted moreover that the sinusoidal groove 17, formed in the shaft 7, is identical to that shown in FIGS. 1, 2, 4 and 5. As shown in FIGS. 6 and 8, the cap 37 may be covered by another cap 42.

The fuze according to the invention operates in the following manner:

When the projectile carrying the fuze is fired, due to the positive acceleration imparted to said projectile the pin 34 (made of aluminium or lead, for example) is cut off, in view of the inertia of the plunger 25 which leaves the plate 1 by the rear. The drum 14 (FIGS. l, 2) or 14a (FIGS. 6, 7), thus liberated is then under the action of the spiral spring 9 which has been wound up. This spring therefore imparts to the drum 14 or 14a a rotary movement which tends to bring said drum from the safety position (FIGS. l, 2 and FIGS. 6, 7) to the armed position (FIGS. 4, and FIGS. 8, 9). However, this rotary movement is delayed by the combined action of the lug 18 and of the groove 17, since the extremity 22 of lug 18 compels the drum to combine its rotary movement with an alternating axial movement.

According to FIGS. 1 to 5, as soon as the drum 14 has commenced its movement, the detonator 26 is 4freed by displacement of the ball 28 (FIG. 5), so that ignition, brought about by the impact of the tiring pin 33 and the detonator 26 can take place when the fuze undergoes a deceleration along its trajectory. However, in order that the explosion may be transmitted from the detonator 26 to the explosive charge 6, it is necessary Ifor the drum 14 to bring the detonator 26 in proximity of the central orifice 2 (see FIGS. 4 and 5).

In the embodiment according to FIGS. 6 to 9, the unlocking of the drum and its compound movement proceed in the same manner. However, in order that the ignition may take place, it is necessary in this embodiment that the drum 14a brings the detonator 26 into a position opposite to the ixed point of the tiring pin 40 (FIG. 8).

The fuzes hereinabove described are particularly suitable for use with rifle or pistol grenades. They may be mounted in the head or into the base of the projectile.

What I claim is:

1. A percussion fuze comprising a mounting plate, an eccentric shaft extending parallel to the axis of said plate and integral therewith, a drum having a central aperture .4 and mounted for both rotation Iand axial movement with respect to said shaft, a firing pin, a detonator which is carried by said drum, a spiral spring of which one end is fast with the plate while the other end is fastened to the drum, and rotation delaying means including a generally sinusoidal groove being formed over at least a portion of the surface of said shaft, the frequency axis of said groove extending in the direction of rotation of the drum and a lug fast with the drum and engaging in said groove for following the path of said groove, providing combined axial and rotary movement of said drum with respect to said shaft, said shaft having an axial recess which accommodates the spiral spring.

2. A percussion fuze comprising a mounting plate, an eccentric shaft extending parallel to the axis of said plate and integral therewith, a drum having a central aperture and mounted for both rotation and axial movement with respect to said shaft, a lfiring pin, a detonator which is carried by said drum, a spiral spring of which one end is fast with the plate while the other end is yfastened to the drum, and rotation delaying means including a generally sinusoidal groove being formed over at least a portion of the surface of said shaft, the frequency axis of said groove extending in the direction of rotation of the drum and a lug fast with the drum and engaging in said groove for following the path of said groove, providing combined axial and rotary movement of said drum with respect to said shaft, said drum being formed with two eccentric apertures, one of said apertures serving to accommodate the detonator and the remaining aperture receiving the extermity of a plunger which, in a safety position, passes through said plate, the aperature of said drum accommodating said detonator being provided in an upper portion thereof with a ring pin fast with said drum, said drum being formed with a transversely extending bore opening into the orifice accommodating the detonator, and further including a ball being lodged in said bore and projecting, in the safety position, above the detonator, there )being a finger extending parallel to the drum axis and fast with the plate for holding said ball within the Ibore.

References Cited UNITED STATES PATENTS Holmes 102-82 BENJAMIN A. BORCHELT, Primary Examiner.

G. H. GLANZMAN, Assistant Examiner.

U.S. Cl. XR. 

